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Buyers' Guide - Air Back Daypacks

Tired of hot, sweaty back syndrome in summer, it's air backs to the rescue time :-)


Posted: 30 May 2007
by Jon

As winter drifts aimlessly into spring and spring metamosphoses seamlessly into the glorious heat of the classic British summer, you may notice your pack becoming a tad damp and sweaty.

That's not surprising really as traditional padded back systems have two major disadvantages, first they prevent air from reaching your back markedly reducing the area available to radiate excess heat outwards and heating you up generally.

Second, most foam-backed packs use wicking fabric in an attempt to move moisture away from your clothing. Unfortunately when faced with lots of sweat these and the foam underneath them tends to become unpleasantly saturated like a big sponge. Yuk...

In an attempt to make things more bearable, several pack manufacturers have produced vented back systems designed to allow air to flow over you back and increase cooling. Here's what you need to know if you're after one...


First Principles

There are two major takes on improving back cooling, but we're not really going to bother with the first which consists of cunning channels and funnels in the back pad intended to channel hot and cold air around.

Why aren't we bothering? Simple, in our experience, they don't make a blind bit of difference. Which leaves you with systems which are designed to hold the pack away from your back allowing air to circulate and cool your body. We'll also take a look at non-absorbent back systems, which may not improve cooling, but at least avoid wet sponge syndrome.


Open Trampolene

It all began with what we're going to call the Open Trampolene. Early Lowe Alpine and current Berghaus and Deuter packs all use this system. Essentially the back of the pack is arched away from the back creating an air gap and a mesh sheet rests against the back.

They're definitely an improvement on conventional back systems and definitely allow more air to reach the back. One drawback is that as much as 60 per-cent of a mesh sheet can actually be solid, so the venting may not be as extensive as it appears. Berghaus has tackled this on their latest Freeflow IV system by reducing the total area of mesh using cut-aways.

Lowe Alpine chose to abandon the mesh method altogether. Other drawbacks are that the arch of the back area significantly reduces the internal volume of the pack and make it a tad banana shaped. With heavier loads, the wide air gap can mean that the pack levers away from the back and feels unstable and, in cold weather, wind blowing between body and pack can make things feel distinctly chilly... On the plus side, the plastc mesh fabrics don't absorb moisture.

Reasonable venting, doesn't absorb moisture.
Cold in wintry conditions, heavy loads lever pack away from back.


Closed Trampolene

A few companies have taken the 'open trampolene' design and refined it, notably Osprey with their Atmos and Terra packs, Haglofs and - coming soon - Gregory.

They use a smaller air gap and a closed side along with a flexible frame which moves easily as the torso twists and bends. There's still a mesh back but because the sides aren't open, less air circulates meaning that they're not as cooling as the more open designs.

The pay-off seems to be better load transfer onto the back and a better carry without the feeling of the load levering away from your back. They also avoid absorbing moisture, just like the open versions. Arguably a better all-year design because of the closed sides, but not as cooling in really hot condtions.

Better carry thanks to smaller air gap and better load transfer. Non absorbent.
Not as cooling as open-sided designs when things get hot.


Mind The Gap

After years using the open trampolene-type system, Lowe Alpine has switched to what they 're calling Pure Air Zone. Rather than using mesh which can be around 60 per-cent solid, they've designed a simple back system which holds the pack away from the body with pads at the top and bottom leaving a total air gap in between.

The system cools really well, but also seems to carry better than the trampolene versions with big air gaps, though not quite as well as the Osprey or Gregory versions making it, arguably, the idea compromise between cooling and carrying.

You still get wind chill from the open sides in winter, but the summer venting performance is good.

No mesh means better cooling performance.
Things can still feel chilly in winter windiness.


Non Absorption

A slightly different approach to the problem is simply to create a back system that's non-absorbent. Most notable, The North Face uses an EVA foam-based system called E-VAP on some of their hydration and multi-sport packs.

The EVA is closed-cell foam so it doesn't absorb moisure. Holes in the foam are intended to allow air to circulate and cool the user, but in our experience the effect is minimal, more importantly, the back system doesn't become unpleasantly and uncomfortably saturated either with sweat or rain. A Pure Air Zone type system with EVA pads would be interesting.

Non absorbent and comfortable even in damp conditions.
EVA foam tends to be quite firm, not particularly cooling even with perforations.


Lumbar Packs

Finally, the increasing light weight and compactness of modern clothing means y may simply be able to bypass the whole pack question by using a lumbar pack or 'bum bag' - fanny pack if you're a North American...

The big plus is that a well-designed one transfers the load directly onto your hips and leaves most of your back exposed and venting. The downside is limited volume and weight capacity. Lumbar packs are a subject in themselves, but if you're carrying a light, compact load in hot conditions, they're hard to beat.

Most of back area unencumbered for great cooling.
Limited load and volume capabilities.


More Help And Advice

This article should have given you some basic pointers. The good news is that there's a load more advice on OUTDOORSmagic:

Ask on the gear forum about general issues or specific items.

Check the member reviews section for user experiences of kit.

See OM editorial reviews on the front of the site for our impressions.

Ask Richard Gear if you have a specific question you need answering.


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